Paper-finishing calenders

ABSTRACT

A paper-finishing calender capable of combining the action of a conventional calender with a supercalender. A stack of hard rolls includes top and bottom rolls and a plurality of intermediate rolls situated therebetween. A paper roll is situated beside and cooperates with at least one of the intermediate rolls to achieve the action of a supercalender therewith. In this way it is possible to avoid the use of a separate unit for the purpose of achieving a supercalendering action.

United States Patent [191 Holm [ 1 Sept. 16, 1975 [54] PAPER-FINISHING CALENDERS [75] Inventor: Pekka Holm, Voikkaa, Finland [73] Assignee: Valmet 0y, Finland [22] Filed: Dec. 18, 1973 [21] Appl. No.: 425,806

[30] Foreign Application Priority Data Dec. 22, 1972 Finland 3640/72 [52] US. Cl. 100/162 R; lOO/l73 [51] Int. Cl. B30B 3/04 [58] Field of Search lOO/l55-176; 162/361, 362

[56] References Cited UNITED STATES PATENTS 1,423,969 7/1922 Schurmann [00/162 R 2,908,964 10/1959 Appenzeller 100/155 R X 3,610,137 10/1971 Brafl'ord lOO/l61 FOREIGN PATENTS OR APPLICATIONS 18,421 6/1882 Germany l0O/l62 R Primary ExaminerPeter Feldman Attorney, Agent, or Firm-Steinberg & Blake [5 7] ABSTRACT A paper-finishing calender capable of combining the action of a conventional calender with a supercalender. A stack of hard rolls includes top and bottom rolls and a plurality of intermediate rolls situated therebetween. A paper roll is situated beside and cooperates with at least one of the intermediate rolls to achieve the action of a supercalender therewith. In this way it is possible to avoid the use of a separate unit for the purpose of achieving a supercalendering action.

7 Claims, 2 Drawing Figures PAPER-FINISHING CALENDERS BACKGROUND OF THE INVENTION The present invention relates to the finishing of paper.

In particular, the present invention relates to a calender which combines the features of a conventional calender with the features of a supercalender.

As is well known, during the finishing of paper, a stack of calender rolls, generally made of hard metal and referred to below as hard rolls, is utilized for giving the paper the required finish. The paper is lapped around the stack of hard rolls travelling in zigzag fashion alternately around the successive rolls through the nips thereof so that the paper will be properly finished at its surface.

However, conventional hard roll calenders cannot give paper a high gloss or finish and smoothing effect which is in many cases highly desirable. Therefore, in order to obtain the required gloss at the surface of the paper it is common practice to use in addition to conventional calenders a supercalender where, for example, alternate hard rolls are replaced with paper rolls. Such a supercalender will give the paper the required high finish.

However, with conventional arrangements it is necessary to use two calenders for this purpose. As the paper leaves the first calender it is wound on a reel and then delivered to the supercalender which conventionally forms a separate unit for further treating the paper, this separate unit being in addition to the conventional paper-finishing structure.

The use of two separate calenders as set forth above represents a serious drawback. Thus, not only is additional equipment and space required, but in addition the time required to achieve the paper finished with the desired high gloss is increased and the labor costs are increased because of the necessity of transferring a reel of paper from the first hard-roll calender to the supercalender.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide a calender construction which will avoid the above drawbacks.

In particular, it is an object of the present invention to provide a calender construction where a single unitary calender assembly is capable of performing both the functions of a conventional calender composed entirely of hard rolls and a supercalender which includes paper rolls.

Thus, it is an object of the present invention to provide with a single calender all of the operations which formerly required two calenders.

As a result it is possible with the invention to achieve a number of advantages. Thus, there is a saving of space and cost simply by combining the two types of calender into a single calender. In addition, there is the further advantage from the fact that the entire finishing of the paper including the action resulting from supercalendering can take place faster than has hitherto been possible because only a single step is required in the paper finishing operation instead of the previously required two steps.

In accordance with the invention the calender comprises a stack of hard rolls including at least top and bottom rolls and a plurality of intermediate rolls situated therebetween. Such a stack can operate in the manner of a conventional calender composed entirely of hard rolls. With the calender of the invention, however, at least one paper roll is situated beside and urged against one of the intermediate rolls to achieve with the latter the action of a supercalender.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way of example in the accompanying drawings which form-part of this application and in which:

FIG. 1 is a schematic end elevation of one embodiment of a calender according to the invention; and

FIG. 2 is a schematic end elevation, partly in section, illustrating a further embodiment of a calender according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, there is schematically illustrated therein a common calender composed only of hard rolls. This calender includes the top roll la and the bottom roll 1b and the pair of intermediate rolls 2a and 2b sitauted therebetween. All of these rolls may be made of hard metal as is well known. These top and bottom rolls la and lb and the intermediate rolls 2a and 2b press against each other in a well known manner and all of the axes of these rolls are located in a common vertical plane. The paper web 4 is guided in a known way in the direction indicated by the arrow a so that the paper web is guided first through the nip between the rolls 1a and 2a to be lapped around the right side of the roll 2:: before passing through the nip of the intermediate rolls to travel around the left side of the roll 2b, as viewed in FIG. 1, before leaving the calender in the manner shown schematically in FIG. 1.

In accordance with the present invention the above conventional calender is provided with paper rolls 3a and 3b. Such paper rolls are well known in connection with supercalenders. Thus, these additional rolls 3a and 3b which are referred to as paper" rolls are sometimes also referred to as filled rolls and are made of a material possessing resilient or elastic properties. The filling required for such rolls is obtained by compressing fabrics, papers, or nonwoven mats of cellulose fiber under high pressure. One of the paper rolls, namely the roll 3a, is placed beside the upper intermediate roll 2a, at the side of the latter which is lapped by the paper web 4. The other paper roll 3b is situated beside the other intermediate roll 2b, at the side of the latter which is lapped by the paper web 4. These paper rolls 3a and 3b are urged in a well known manner toward the hard intermediate rolls 2a and 2b, respectively, and they can be moved to an inoperative position where they are maintained out of contact with the hard rolls 2a and 2b, also in a manner well known in the art. Such displacement of the paper rolls to positions where they do not participate in the finishing is provided, for example, when the paper web 4 is to be treated only by the hard rolls so that the paper rolls are not required. Of course, it is also possible, if desired, to place only one of the paper rolls 3a and 3b in operation in order to achieve a desired finish. FIG. 1 schematically illustrates a pair of means 5, also known in the art, operatively connected with the pairs of cooperating rolls 2a, 3a and 2b, 3!; for synchronizing the hard rolls and the paper rolls which cooperate therewith so that each pair of cooperating hard and paper rolls will have the same peripheral velocity. The paper rolls 3a and 3b and the top and bottom hard rolls 1a and 1b may have the construction of known Kusters rolls.

The calender of the invention which is illustrated in FIG. 2 has the same number of hard rolls and paper rolls as the embodiment of FIG. 1. Moreover, the rolls shown in FIG. 2 correspond to those in FIG. 1 and operate in the same way so that they are in effect the equivalent thereof. However, with the embodiment of FIG. 2 while the top and bottom rolls Ia and lb still have their axes situated in a common vertical plane, the intermediate rolls 2a and 2b have their axes located in a plane which is inclined with respect to the vertical plane, as is apparent from FIG. 2. The paper rolls 3a and 3b, however, still cooperate in the same way with the displaced rolls 2a and 2b of FIG. 2. It will be noted that the direction of inclination of the plane which contains the axes of the rolls 2a and 2b of FIG. 2 is such that the upper intermediate roll 2a has been displaced toward the paper roll 3a which is urged toward the intermediate roll 2a, and in the same way the lower intermediate roll 2b has been displaced in the direction toward the paper roll 3b which is urged toward the roll 2b. In other words the parallel axes of the cooperating rolls 2a and 3a are located on one side of the vertical plane which contains the axes of the top and bottom rolls la and lb while the parallel axes of the rolls 2b and 3b are located on the other side of this vertical plane. With the embodiment of FIG. 2 the top and bottom rolls la and lb as well as the paper rolls 3a and 3b have the construction of Kusters rolls, but rolls of other structural types can be used.

It has been found from experience to be advantageous to synchronize the speeds of rotation of the cooperating hard and paper rolls so that they will have the same peripheral velocities as provided by the pair of means 5, shown in FIG. I and described above. Also,

the arrangement of FIG. 2 where the pair of intermediate rolls are displaced to have their axes located in the inclined plane has proved to be of advantage. Also, the use of Kusters rolls for the top and bottom rolls as well as for the paper rolls is preferred.

It is obvious that the invention is not confined merely to the embodiment examples shown in the drawings, which may be modified in many different ways within the scope of the invention. For instance, the calender consisting of hard rolls may have a greater number of hard rolls between the extremely positioned hard rolls. The number of paper rolls may also be greater than two.

What is claimed is:

I. In a paper-finishing calender, a stack of hard rolls including top and bottom rolls and a plurality of intermediate rolls situated therebetween for guiding a web through nips between said hard rolls while said web is lapped at least around said plurality of intermediate rolls, and at least one paper roll situated beside and cooperating only with one of said intermediate rolls for acting on a web lapped around the latter intermediate roll while the web travels from said one intermediate roll to the next hard roll for achieving the action of a supercalender with said one intermediate roll without lapping the web around said paper roll.

2. The combination of claim 1 and wherein a means cooperates with said paper roll and said one intermediate roll cooperating therewith to synchronize the latter rolls so that they have the same peripheral velocity.

3. The combination of claim 1 and wherein all of the hard rolls respectively have axes located in a common plane while said paper roll has an axis situated outside of and extending parallel to said common plane and the axis of said one intermediate roll.

4. In a paper-finishing calender, a stack of hard rolls including top and bottom rolls and a plurality of intermediate rolls situated therebetween, and at least one paper roll situated beside and cooperating with one of said intermediate rolls for achieving the action of a supercalender therewith, said hard rolls including at least a pair of top and bottom rolls respectively having axes located in a common vertical plane and at least one pair of intermediate rolls situated between said top and bottom rolls and respectively having parallel axes located in a second plane which is inclined with respect to said vertical plane, and a pair of said paper rolls respectively cooperating with said intermediate rolls for achieving the action of a supercalender therewith.

5. The combination of claim 4 and wherein one of said intermediate rolls and the paper roll cooperating therewith are located on one side of said vertical plane while the other of said intermediate rolls and the paper roll cooperating therewith are located on the other side of said vertical plane.

6. The combination of claim 1 and wherein said top and bottom rolls and said paper roll have the construction of Kusters rolls.

7. The combination of claim 1 and wherein a pair of said .paper rolls are situated beside and cooperate with a pair of said intermediate rolls to achieve the action of a supercalender therewith, the latter pair of intermediate rolls being situated one next to the other. 

1. In a paper-finishing calender, a stack of hard rolls including top and bottom rolls and a plurality of intermediate rolls situated therebetween for guiding a web through nips between said hard rolls while said web is lapped at least around said plurality of intermediate rolls, and at least one paper roll situated beside and cooperating only with one of said intermediate rolls for acting on a web lapped around the latter intermediate roll while the web travels from said one intermediate roll to the next hard roll for achieving the action of a supercalender with said one intermediate roll without lapping the web around said paper roll.
 2. The combination of claim 1 and wherein a means cooperates with said paper roll and said one intermediate roll cooperating therewith to synchronize the latter rolls so that they have the same peripheral velocity.
 3. The combination of claim 1 and wherein all of the hard rolls respectively have axes located in a common plane while said paper roll has an axis situated outside of and extending parallel to said common plane and the axis of said one intermediate roll.
 4. In a paper-finishing calender, a stack of hard rolls including top and bottom rolls and a plurality of intermediate rolls situated therebetween, and at least one paper roll situated beside and cooperating with one of said intermediate rolls for achieving the action of a supercalender tHerewith, said hard rolls including at least a pair of top and bottom rolls respectively having axes located in a common vertical plane and at least one pair of intermediate rolls situated between said top and bottom rolls and respectively having parallel axes located in a second plane which is inclined with respect to said vertical plane, and a pair of said paper rolls respectively cooperating with said intermediate rolls for achieving the action of a supercalender therewith.
 5. The combination of claim 4 and wherein one of said intermediate rolls and the paper roll cooperating therewith are located on one side of said vertical plane while the other of said intermediate rolls and the paper roll cooperating therewith are located on the other side of said vertical plane.
 6. The combination of claim 1 and wherein said top and bottom rolls and said paper roll have the construction of Kusters rolls.
 7. The combination of claim 1 and wherein a pair of said paper rolls are situated beside and cooperate with a pair of said intermediate rolls to achieve the action of a supercalender therewith, the latter pair of intermediate rolls being situated one next to the other. 